Field of the Invention
The present invention relates to a film forming apparatus for forming a film on a substrate.
Background Art
Japanese Patent Laid-Open No. 2001-189308 discloses a film forming apparatus that generates a plasma between an upper electrode having gas introduction holes through which a material gas used for film forming passes and a lower electrode. In this film forming apparatus, the number of gas introduction holes per unit area is changed with respect to in-plane positions in the upper electrode so that a film forming gas is concentratedly introduced to a place where the film forming speed is low.
There is a problem that if the density of the gas introduction holes in the electrode is adjusted as in the art disclosed in Japanese Patent Laid-Open No. 2001-189308, not only the amount of supply of the material gas but also the plasma concentration is changed. Thus, film thickness uniformity in a substrate surface is improved by sacrificing the controllability of the film quality.